Explanation:
Globular star cluster
Omega Centauri
is some 15,000 light-years away and 150 light-years in
diameter.
Packed with about 10 million stars,
Omega
Cen is the largest of 200 or
so known globular clusters that roam the
halo of our Milky Way galaxy.
This intriguing color picture combines a visible light image of the
cluster in blue hues
with infrared image data from the Spitzer
Space Telescope.
The Spitzer data includes
images in two infrared bands, one shown in green
and one in red.
Both infrared bands are sensitive to light from the cool, giant stars in
the cluster.
Adding
the red and green
colors together creates yellow, showing off
the cluster's giant stars as yellow spots.
Of course, red spots also indicate cool, giant stars in the image, but
some of the red spots are even more distant background galaxies.
Also known simply as
Red Giant Stars,
they represent
a stage in the
life-cycle
of stars more evolved than our own Sun, a stage
the Sun will reach in about 5 billion years.
Dust grains formed in the atmospheres of cool, giant stars are
ultimately involved in the formation of other stars
and planets.